1. Field of the Invention
The present invention relates generally to an electroacoustic transducer and more particularly is directed to a headphone for reproducing an audio signal.
2. Description of the Prior Art
A headphone has hitherto been proposed to have a housing incorporating therein a speaker unit which is inserted into an auricle as shown in FIG. 1. In FIG. 1, reference numeral 1 designates a housing of substantially circular truncated cone shape into which a speaker unit 2 is incorporated. Reference numeral 3 designates a protector member disposed at the position opposite to a diaphragm 2a of the speaker unit 2. A large number of apertures are bored through the protector member 3 to pass therethrough the sound emanated from the speaker unit 2. Reference numeral 4 designates a cord supporting member and 5 a cord.
Such prior art headphone is inserted into an auricle A and secured therein in shown in FIG. 2. Generally, as the common shape of the auricle A of a human ear, there is a recess of substantially circular truncated cone, namely, a so-called cavum concha C at the forward side surface of which the entrance of an external auditory meatus B lies. At the lower side of the cavum concha C, a so-called tragus D and an anti-tragus E protrude toward the upper side of the cavum concha C from both sides thereof to from a gap of substantially U-shape, namely, so-called inter-tragus notch F between the tragus D and the anti-tragus E. The housing 1 of the headphone is positioned within the cavum concha C and held between the tragus D and the anti-tragus E and the cord supporting member 4 is disposed in the notch F.
By the way, the prior art headphone shown in FIG. 1 is inserted into the auricle A and secured therein by utilizing the shape of the auricle A common to the human ear. However, the auricle A of the human ear is different in size dependent upon a user and therefore the headphone may be either too large or too small for the user. Thus, there is a disadvantage that the user of the headphone frequently feels pain too strong permit use of the headphone.
Further, since the external auditory meatus B obliquely extends forwardly relative to the cavum concha C, the headphone positioned within the cavum concha C and facing the head inevitably causes the diaphragm 2a of the speaker unit 2 thereof to be inappropriately angled relative to the external auditory meatus B. The shapes of the external auditory meatus B and the periphery of its entrance are different, dependent upon users. As a result, when the headphone is inserted into the auricle A with the diaphragm 2a oriented slantwise relative to the external auditory meatus B, the sound radiated from the diaphragm 2a is reflected by the external auditory meatus B and around the entrance of the external auditory meatus B and then reached to the eardrum or tympanum. Thus, the sounds reflected by the external auditory meatus B and around the entrance of the external auditory meatus B of each different shape provide tone quality that is different depending on the individual.